The Palaeo-Kambaniru river mouth, Sumba, East Nusa Tenggara, Indonesia: A record of strongly seasonal catastrophic flow in a monsoon-controlled deltaic complex

The Kambaniru River valley near the city of Waingapu preserves a thick succession of coarse-grained fluvial-deltaic sediment deposited during the Late Pleistocene. This succession incises through a thick uplifted coral reef terrace succession and records intervals of highly episodic flow events during the last glacial interval. The occurrence of intraclastic, coarse sand/gravel matrix olistostromes in several areas attests to the occasionally catastrophic nature of flow in the ancestral Kambaniru River. Small to moderate-sized coral-rich reefs and laterally restricted reef terraces occur on delta-front conglomerate successions at multiple horizons through the study interval. These reefs record both intervals of low flow as well as periodic river-mouth avulsion episodes. Comparison of radiometric dates obtained from pelecypod and coral material from both deltaic successions and laterally adjacent coral reef terrace intervals indicates that uplift/subsidence history of the terraces differs from that of the valley and that correlation between the two should be taken with care.

The Continental Crust beneath the Western Amerasia Basin: Mechanisms of Subsidence

—The western part of the large Amerasia Basin in the Arctic Ocean comprises the smaller basins of Podvodnikov and Makarov. Judging by the sedimentary structure and the crustal subsidence history, both basins were developed on the continental crust despite their 3–4 km water depths. By the early Miocene, prior to the rapid formation of the basins, the crustal surface had been close to the sea level for a long time. Lithospheric stretching had a minor input to the subsidence, which was rather driven mainly by the prograde metamorphism of gabbro in the lower crust and its transformation into denser eclogite. The mechanism of subsidence associated with the metamorphic transformation from gabbro to eclogite implies that high-velocity eclogite belongs to the lower continental crust metamorphosed under the effect of mantle fluids. This idea undermines the seismic and gravity basin models that commonly attribute mafic eclogite to the sub-Moho lithospheric mantle on the basis of P-wave velocities similar to those in peridotite and interprets the crust beneath the Podvodnikov and Makarov basins as thin continental and oceanic crustal types, respectively.

HYDROCARBON GENERATION DYNAMICS OF KUREIKA SYNCLINE KUONAMKA SOURCE ROCK BASED ON THE DATA OF CHIRINDINSKAYA-271 WELL

Based on the materials of Chirindinskaya-271 well Kureika syncline sedimentary boundary subsidence history has been performed, the history of source rock catagenesis before trap magmaizm has been recreated, the time of kuonamka source rock getting into oil window has been set, hydrocarbon generation extent has been calculated till the moment before trap magmatism.

Constraining Basin Parameters Using a Known Subsidence History

Temperature history is one of the most important factors driving subsidence and the overall tectono-stratigraphic evolution of a sedimentary basin. The McKenzie model has been widely applied for subsidence modelling and stretching factor estimation for sedimentary basins formed in an extensional tectonic environment. Subsidence modelling requires values of physical parameters (e.g., crustal thickness, lithospheric thickness, stretching factor) that may not always be available. With a given subsidence history of a basin estimated using a stratigraphic backstripping method, these parameters can be estimated by quantitatively comparing the known subsidence curve with modelled subsidence curves. In this contribution, a method to compare known and modelled subsidence curves is presented, aiming to constrain valid combinations of the stretching factor, crustal thickness, and lithospheric thickness of a basin. Furthermore, a numerical model is presented that takes into account the effect of sedimentary cover on thermal history and subsidence modelling of a basin. The parameter fitting method presented here is first applied to synthetically generated subsidence curves. Next, a case study using a known subsidence curve from the Campos Basin, offshore Brazil, is considered. The range of stretching factors estimated for the Campos basin from this study is in accordance with previous work, with an additional estimate of corresponding lithospheric thickness. This study provides insight into the dependence of thermal history and subsidence modelling methods on assumptions regarding model input parameters. This methodology also allows for the estimation of valid combinations of physical lithospheric parameters, where the subsidence history is known.

Quantitative analysis for compaction trend and basin reconstruction of the Perth Basin, Australia: Limitations, uncertainties and requirements

<p>This study quantifies compaction trends of Jurassic-Quaternary sedimentary units in the Perth Basin, and applies the trends to reconstruct the sedimentation and subsidence history with 2D and 3D models. BasinVis 2.0, a MATLAB-based program, as well as MATLAB 3D surface plotting functions, ‘Symbolic Math’ and ‘Curve Fitting’ toolboxes are used to analyze well data. The data were collected from fourteen industry wells and IODP Site U1459 in a study area (200x70 km2) on an offshore part of the basin, which were arranged for four successive stratigraphic units; Cattamarra, Cadda, Yarragadee, and post-breakup sequences. The Perth Basin is a large north-south elongated sedimentary basin extending offshore and onshore along the rifted continental margin of southwestern Australia. It is a relatively under-explored region, despite being an established hydrocarbon producing basin. The basin has developed by multiple episodes of rifting, drifting and breakup of Greater Indian, Australian and Antarctic plates since the Permian. The basin consists of faulted structures, which are filled by Late Paleozoic to Cenozoic sedimentary rocks and sediments. After deltaic-fluvial and shallow marine deposition until early Cretaceous time, carbonate sedimentation has prevailed in the basin, which is related to the post-rift subsidence and the long-term northward drift of the Australian plate.</p><p>High-resolution porosity data of Site U1459 and well Houtman-1 were examined to estimate best fitting compaction trends with linear, single- and two-term exponential equations. In the compaction trend plot of Site U1459 (post-breakup Cenozoic carbonates), the linear and single-term exponential trends are relatively alike, while the two-term exponential trend has abrupt change near seafloor due to highly varying porosity. The compaction trends at well Houtman-1 (Jurassic sandstones) are alike in the estimated interval, however initial porosities are quite low and different. In the compilation plot of the two wells, the two-term exponential trend presents better the porosity distribution, by adopting a trend change as estimation overfitting, by the lithologic transition from carbonates to sandstones. The abrupt trend change suggests that the multiple piece-wise compaction trend is suitable for the Perth Basin. The compaction trends are used to quantify the sedimentation profile and subsidence curves at Site U1459. 2D and 3D models of unit thickness, sedimentation rate and subsidence of the study area are reconstructed by applying the exponential trend to the stratigraphic data of industry wells. The models are visualized using the Ordinary Kriging spatial interpolation. The results allow us to compare differences between compacted (present) and decompacted (original) units through depth and age. The compaction trend has an impact on thickness restoration as well as subsidence analysis. The differences become larger with increasing depth due to the rising compaction effect during burial. Other factors can deviate the compaction trend further through age. This phenomenon highlights the fact that the restoration of largely compacted (usually deeper or older) layers is crucial to reconstruct sedimentation systems and basin evolution. This has often been underestimated in academic and industry fields. This study suggests that researchers apply the appropriate compaction trend estimated from on-site data for basin reconstruction and modelling.</p>